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Methods used for the Demographics Data

SURVEY PARTICIPATION RATE: count of the number of miners with a valid x-ray
during the survey period (NUMBER OF MINERS EXAMINED) divided by the count
of the names on the most recent mine rosters submitted to NIOSH by the mine
operators (ESTIMATED CURRENT EMPLOYMENT).

AGE - MEAN: summation of the calculated age at time of the x-ray divided by
count of participating miners who provided their date of birth (N).

TENURE - MEAN: summation of the reported years in various underground
mining occupations divided by count of participating miners with a
completed work history (N).

TENURE AT THE FACE - MEAN: summation of the reported years of working at
the face divided by count of participating miners who reported working at
the face (N).

Methods used for the Prevalence of Disease Data

>= 1/0 or PMF: number of x-rays with a final determination (consensus
based upon NIOSH procedures) of the International Labour Office (ILO) small
opacity profusion category 1/0 or higher or with the presence of large
opacities, divided by the number of participating miners with a valid
x-ray.

>= 2/1 or PMF: number of x-rays with a final determination (consensus
based upon NIOSH procedures) of the International Labour Office (ILO) small
opacity profusion category 2/1 or higher or with the presence of large
opacities, divided by the number of participating miners with a valid
x-ray.

PMF: number of x-rays with a final determination of ILO large opacity
category "A", "B", or "C" divided by the number of participating miners
with a valid x-ray.

ADVANCED: number of x-rays with a final determination of ILO small opacity
profusion category 2/1 or higher and presence of symbol "ax" (coalescence
of small opacities) or ILO large opacity category of "A", "B", or "C"
divided by the number of participating miners with a valid x-ray.

Methods used for the Distribution of Radiographic Findings

PROFUSION OF SMALL OPACITIES, LARGE OPACITIES & SYMBOLS: count and percent
of the x-rays using the final determination of the ILO small opacity, the
final determination of the ILO large opacity, and symbol "ax" (coalescence
of small opacities).